Cholinergic synapses have adrenergic receptors and are modified by adrenergic drugs. d-Amphetamine depresses cholinergic transmission at autonomic ganglia, however it has not been determined whether d-amphetamine acts at the same receptors and by the same mechanism of action as the catecholamines. The experiments in this project are designed to determine the cellular mechanisms for the actions of d-amphetamine on ganglionic transmission. Electrophysiological techniques will be used to study the effects of d-amphetamine on the isolated stellate ganglion of the hamster. Concentration-response curves, time course of action, interaction with alpha and beta adrenergic receptors, and interaction with epinephrine will be explored with extracellular recordings from the postganglionic nerve of the stellate ganglion. The cellular mechanisms of ganglionic blockade and facilitation will be studied with intracellular recording methods to determine whether the blockade and facilitaton are due to presynaptic or postsynaptic action of d-amphetamine. The mechanisms of action for d-amphetamine will be compared to the mechanisms of action for epinephrine. The action of d-amphetamine will also be explored in hamsters that have been chronically pretreated with d-amphetamine (administered in their drinking water). The chronic experiments will clarify whether prolonged administration of d-amphetamine modifies the physiological and pharmacological properties of ganglionic transmission. This will give us a better understanding of the pharmacological role of adrenergic receptors in cholinergic synapses.